Forum für Wissenschaft, Industrie und Wirtschaft

Hauptsponsoren:     3M 
Datenbankrecherche:

 

Viable and fertile fruit flies in the absence of histone H3.3

13.11.2012
Histones – proteins that package DNA – affect cell function differently than previously assumed: the cell doesn’t need the histone H3.3 to read genes. Molecular biologists from the University of Zurich demonstrate that fruit flies can develop and reproduce in the absence of this histone. Additionally, cell division works without a histone modification previously deemed crucial.

Histones are proteins that are found in the cell’s nucleus, where they are present in complexes with DNA and are presumed to play a regulatory role in all processes that take place on the DNA. These processes include transcription, namely RNA synthesis, and the duplication of DNA during cell division.


Drosophila wing imaginal disc: Non-stained cells, areas in black, can not modify their histone H3 at the lysin. But the cells can divide and read genes. Dark blue represents non-mutant cells, cyan represents the modification at the lysin.

Picture: UZH

Until now, the function of the individual histones in the various processes could only be determined indirectly. Molecular biologists Konrad Basler and Martina Hödl from the University of Zurich for the first time directly studied the function of two histones and one histone modification – with surprising results: Viable and fertile organisms develop in the absence of the histone known as H3.3. Additionally a particular histone modification was believed to be crucial for the activation of gene transcription.

However, the researchers were able to demonstrate that this is also not the case. The established models for the role and function of histones and their modifications during the transcription and cell-division need to be revised.

Fertile fruit flies despite lack of histone H3.3

For their study, Basler and his postdoctoral student Hödl used the fruit fly Drosophila melanogaster, the genome of which has been fully decoded. In an initial experiment, the scientists switched the two histone variants H3.2 and H3.3 in the cells. In normal (i.e. non-manipulated) cells, histone H3.2 is only expressed in one specific phase of the cell cycle, the so-called S phase. Histone H3.3, however, is always expressed. Consequently, it was assumed that histone H3.3 plays a key role in transcription, especially in reading genes. Thus, the general consensus was that RNA synthesis would be restricted in the absence of histone H3.3. “In our experiment, under lab conditions viable and fertile fruit flies could develop from cells that do not have any H3.3,” explains Hödl, summing up the result that turns the previous understanding on its head. “Organisms also begin to develop from cells without H3.2 but these died in the first larval stage,” Hödl continues.

Genes are switched on and off without histone modification

Histones are modified by different enzymes at different points in the protein. In a second experiment, Basler and Hödl examined the importance of modifications of the fourth amino acid of the protein, a lysine. Modification of this lysine is thought to play a key role in activating and deactivating the transcription of the gene. To test this, the scientists replaced the lysine with non-modifiable amino acids in all the histone H3 genes. The result was another big surprise. “Cells without this specific histone modification are able to divide normally,” explains Basler before adding: “However, they do so considerably more slowly than cells that have not been modified.” Therefore, the modification of this lysine is not essential for the activation of the genes.

The results show that the activation of genes and the inheritance of the ability to activate genes work differently than previously assumed. Clearly, the structure of the transcription process is extremely robust. According to Basler, the role of this common histone modification for cell function has been overestimated in recent years.

Literature:
Martina Hödl, Konrad Basler, Transcription in the Absence of Histone H3.2 and H3K4 Methylation. Current Biology. November 8, 2012. http://dx.doi.org/10.1016/j.cub.2012.10.008
Contact:
Dr. Martina Hödl
Institute of Molecular Life Sciences
University of Zurich
Tel. +41 44 635 31 15
E-Mail martina.hoedl@imls.uzh.ch

Nathalie Huber | Universität Zürich
Further information:
http://www.uzh.ch

More articles from Life Sciences:

nachricht Quasi-sexual gene transfer drives genetic diversity of hot spring bacteria
29.05.2015 | Carnegie Institution

nachricht Scientists use unmanned aerial vehicle to study gray whales from above
29.05.2015 | NOAA National Marine Fisheries Service

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Galapagos-Vulkanismus: Überraschend explosiv

Internationales Vulkanologen-Team präsentiert neue Erkenntnisse zur Eruptions-Geschichte

Vor 8 bis 16 Millionen Jahren gab es im Gebiet der heutigen Galapagos-Inseln einen hochexplosiven Vulkanismus. Das zeigt erstmals die Auswertung von...

Im Focus: Lasers are the key to mastering challenges in lightweight construction

Many joining and cutting processes are possible only with lasers. New technologies make it possible to manufacture metal components with hollow structures that are significantly lighter and yet just as stable as solid components. In addition, lasers can be used to combine various lightweight construction materials and steels with each other. The Fraunhofer Institute for Laser Technology ILT in Aachen is presenting a range of such solutions at the LASER World of Photonics trade fair from June 22 to 25, 2015 in Munich, Germany, (Hall A3, Stand 121).

Lightweight construction materials are popular: aluminum is used in the bodywork of cars, for example, and aircraft fuselages already consist in large part of...

Im Focus: Wie Solarzellen helfen, Knochenbrüche zu finden

FAU-Forscher verwenden neues Material für Röntgendetektoren

Nicht um Sonnenlicht geht es ihnen, sondern um Röntgenstrahlen: Wissenschaftler der Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) haben zusammen mit...

Im Focus: Festkörper-Photonik ermöglicht extrem kurzwellige UV-Strahlung

Mit ultrakurzen Laserpulsen haben Wissenschaftler aus dem Labor für Attosekundenphysik in dünnen dielektrischen Schichten EUV-Strahlung erzeugt und die zugrunde liegenden Mechanismen untersucht.

Das Jahr 1961, die Erfindung des Lasers lag erst kurz zurück, markierte den Beginn der nichtlinearen Optik und Photonik. Denn erstmals war es Wissenschaftlern...

Im Focus: Solid-state photonics goes extreme ultraviolet

Using ultrashort laser pulses, scientists in Max Planck Institute of Quantum Optics have demonstrated the emission of extreme ultraviolet radiation from thin dielectric films and have investigated the underlying mechanisms.

In 1961, only shortly after the invention of the first laser, scientists exposed silicon dioxide crystals (also known as quartz) to an intense ruby laser to...

Alle Focus-News des Innovations-reports >>>

Anzeige

Anzeige

IHR
JOB & KARRIERE
SERVICE
im innovations-report
in Kooperation mit academics
Veranstaltungen

Cannabis – eine andauernde Kontroverse

29.05.2015 | Veranstaltungen

Frauen können nicht alles haben - Männer aber schon?!

29.05.2015 | Veranstaltungen

13. Koblenzer eLearning Tage

28.05.2015 | Veranstaltungen

 
B2B-VideoLinks
Weitere VideoLinks >>>
Aktuelle Beiträge

Galapagos-Vulkanismus: Überraschend explosiv

29.05.2015 | Geowissenschaften

"Drittes Auge": Hightech-Einkaufshilfe für Blinde

29.05.2015 | Innovative Produkte

Brüchiges Erbgut: Neuer Therapie-Ansatz gegen Speiseröhrenkrebs

29.05.2015 | Biowissenschaften Chemie